I found this flat plate fossil in a creek bed on my ranch in SW Texas (Texas hill country, Uvalde co., Fush creek, DRY FRIO river valley). It is c. 9x4 inches by c. 1 inch thick. It seems to be a key stone shape, with a bony porous
inside, covered with a "skin" ( thin as a sheet of paper) with wild complex patterns of streaks and dots on both sides. The "skin" is worn away on the edges , showing the inside porous
core. There is a damaged or perhaps an attachment scar on one side. There seem to be some structure inside the core ( veins ?, or spines ?) . at one end, a tip has a red stain in the pores.
When I first found it in gravels, I picked it up because I thought it was just a flagstone with a interesting pattern , caused by thin layers of (limestone?) that had been weathered into
the swirling patterns. I forgot about it till 6 months ago, looked close and noted the porous bony core, and that the swirling patterns were not weathering at all. I am guessing it might be a stegasorus plate with skin and the patterns maybe decoration or some type of id marking or cooling feature. Or something else completely.But, I need some input as to what it may really be.